i.neuron review ii.relationship between stimuli input iii.nervous system organization iv.brains...

I. Neuron Review

II. Relationship between Stimuli Input

III. Nervous System Organization

IV. Brains

V. Preparation for next lecture

Lecture 14 – Ch. 49: Nervous Systems

The Nervous System

Includes all nerve cells (neurons) and support cells

Specialized “excitable” cells: receive input, integrate, send output

Neurons

synapse

dendrite

synapticterminal

1 Synaptic terminals:Bring signals fromother neurons.

2 Dendrites:Receive signalsfrom other neurons.

3 Cell body:Integrates signals;Coordinates.

4 Action potentialstarts here.

5 Axon: Conductsthe action potential.

6 Synaptic terminals:Transmit signals toother neurons.

7 Dendrites(of other neurons).

5

What parts of neurons are OUTSIDE the CNS?

A. All sensory, motor, and interneurons neurons

B. Sensory neuron dendrites & cell bodies AND motor neuron axons

C. Interneurons only

D. Motor neuron dendrites and interneuron axons

gap

dendrite ofpostsynapticneuron

neurotransmitter

synapticvesicle

synapticterminal

Neurotransmittersignals next neuron.

Signal reaches end of axon.

Synaptic vesicles release neurotransmitter.

Receptor bindsneurotransmitter.

Neurons

Synapse: Region connecting two neurons or neuron and muscle

Neurotransmitter may excite or inhibit the next neuron

Information Coding in the Nervous System:

1) Determine stimulus type (e.g. light / sound / touch)

• All neurons use same basic signal

• Wiring pattern in brain distinguishes stimuli

2) Signal intensity of stimulus

• All signals similar in size (all-or-none response)

• Intensity coded by:

1) Frequency of action potentials

2) # of neurons responding

Stimuli Input

Information Coding in the Nervous System:

Stimuli Input

fires slowly

silent

1

2

fires moderately

silent

1

2

fires rapidly

fires slowly

1

2

Information Coding in the Nervous System:

3) Integrate/coordinate signals

4) Determine Output

Stimuli Input

Neural Pathways Direct Behavior:

• Reflex: Involuntary movement in response to stimulus

• Simplest behavior:

1) Receptor: Detects stimulus

2) Sensory neuron: Sends stimulus message

3) Association neuron: Integrates stimuli

4) Motor neuron: Activates effector

5) Effectors: Performs function (muscle / gland)

REFLEXARCstimulus

effector

receptor

dorsalroot

ventralroot

sensationrelayedto the brain

3 Signal transmittedto a motor neuron by aninterneuron within thespinal cord.

4 Motor neuronstimulates theeffector muscle.

5 Effector musclecauses withdrawalresponse.

1 A painfulstimulus activatesa pain receptor. 2 Signal transmitted

by a pain sensory neuron.

Increased Complexity in Nervous System = Increased centralization

Nerve Net: Nervous tissue woven throughout body (no head)

Nerve Net Cephalization

Cephalization: Nervous tissue centralized in “head” region

Stimuli Input

brain

(c) Octopus(a) Hydra (b) Flatworm

ring of ganglia

diffuse networkof neurons

nerve cords

cerebralganglia(brain)

Brain and spinal cord

Nervous System Organization

1) Bone (Skull; Spinal Cord = vertebrae)

2) Meninges (Triple-layer of connective tissue)

• Contains cerebrospinal fluid (cushioning / nourishment)

3) Blood-brain Barrier

• Selective barrier in blood vessels

Spinal Cord:

Myelin = Insulation around axons

• Increases AP conduction rate

Nervous System Organization

Spinal Cord:

Nervous System Organization

What part of the spinal cord contains motorneuron cell bodies?

A. White matter

B. Dorsal root ganglia

C. Gray matter

D. Ventral roots

PN

SC

NS

Brain and Spinal Cord

Sympathetic nervoussystem

"fight or flight"

Parasympathetic nervoussystem

"rest and repose"

Somatic nervoussystem

(voluntary)

Sensory neuronsregistering external

stimuli

Autonomic nervoussystem

(involuntary)

Sensory Pathways Motor Pathways

Sensory neuronsregistering external

stimuli

Nervous System Organization

Nervous System Organization

If you are surprised by a “predator”, what happens in your nervous system?

A. Sympathetic nervous system increases heart rate

B. Somatic nervous system increases heart rate

C. Autonomic nervous system increases saliva

D. Parasympathetic NS increases saliva secretion

How far can you safely drive behind the car in front if you are travelling at 60 mph?

Thought Question:

Think about: Your reaction time (what has to happen for you to stop if the car in front of you stops?)

How far you go per second (at what speed are you traveling?)

The Brain:

Brains: What are the major differences?

Vertebrate Brains

cerebrum

EMBRYONIC VERTEBRATE BRAIN

SHARK BRAIN

GOOSE BRAIN

HUMAN BRAIN

(a)

(b)

(c)

(d)

cerebrumthalamus

optic lobe

cerebellum

medulla

forebrain midbrain hindbrain

cerebrum midbraincerebellum

cerebrum

midbrain

cerebellum

cerebellummidbrain(inside)

The Brain:

1) Hindbrain:

Automatic BehaviorsA) Medulla: Controls

breathing, heart rate,

blood pressure

B) Pons: Controls

wake/sleep transitions;

sleep stages

C) Cerebellum:

Coordinates movement

spinal cord

meningesskull

cerebellumponsmedulla

hindbrain

Human Brain

The Brain:

2) Midbrain: Relay /

“Screening” Center A) Reticular Formation:

Controls arousal of brain

• Filters sensory input from body

B) Visual / Auditory Reflex Centers

pituitarygland pineal

gland

midbrain- Reticular Formation

Human Brain

The Brain:

3) Forebrain (Cerebrum):

“Seat of Consciousness”

A) Cerebral Cortex

• Two hemispheres (Connection =

Corpus Callosum)

• Left hemisphere controls right side

of body (and vise versa)

cerebralcortex

corpuscallosum

Human Brain

The Brain:

3) Forebrain (Cerebrum)A) Cerebral Cortex

Four regions:

1) Frontal: Primary motor area; complex reasoning

2) Parietal: Primary sensory area

3) Temporal: Primary auditory and olfactory areas

4) Occipital: Primary visual area

Human Brain

OccipitalLobe

ParietalLobe

FrontalLobe

TemporalLobe

OccipitalLobe

primarysensory area

sensoryassociationarea

sensoryassociationarea

primaryvisualarea

primaryvisualarea

visualassociationarea

visualassociationarea

auditory associationarea: languagecomprehension

auditory associationarea: languagecomprehension

memorymemory

speechmotor areaspeechmotor area

higherintellectualfunctions

higherintellectualfunctions

primaryauditoryarea

primaryauditoryarea

premotorareapremotorarea

primarymotor areaprimarymotor area

legleg

trunktrunk

armarm

handhand

faceface

tonguetongue

ParietalLobe

FrontalLobe

TemporalLobe

Human Brain

Motor and Sensory

areas

Human Brain

Which is a correct match between brain region and function:

A. Parietal lobe : visual processing

B. Reticular formation : filters sensory input

C. Cerebellum : controls sleep stages

D. Cerebrum : dictates breathing rate

Cortical Regions Involved in Different Tasks:

Human Brain

Seeing Words

max0

Reading Words Generating Verbs

Hearing Words

The Brain:

hypothalamusthalamus

B) Limbic System

• Produce emotions; form memories

C) Thalamus

• Relays information from body to limbic system / cerebral cortex

3) Forebrain (Cerebrum)

Human Brain

The Brain:

B) Limbic System

• Hypothalamus:

Homeostatic control center

• Amygdala: Produces

sensations of pleasure,

fear, or sexual arousal

• Hippocampus:

Formation of long-term memory

C) Thalamus

• Relays to limbic system /

cerebral cortex

Human Brain

hypothalamus

corpus callosum

limbic regionof cortex

cerebral cortex

amygdala

hippocampus

thalamus

Damage to the hippocampus could result in:

A. Failure to understand speech

B. Reduced fear response

C. Lack of homeostatic control

D. Loss of long-term memory formation

Things To Do After Lecture 14…Reading and Preparation:

1. Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms.

2. Ch. 49 Self-Quiz: #1, 2, 4, 5, 6, 7 (correct answers in back of book)

3. Read chapter 49, focus on material covered in lecture (terms, concepts, and figures!)

4. Skim next lecture.

“HOMEWORK” (NOT COLLECTED – but things to think about for studying):

1. Explain the difference between the somatic and autonomic nervous systems.

2. Diagram a basic neuron – for sensory, motor, and interneurons explain the location of each region with respect to peripheral or central nervous system.

3. Compare and contrast the embryonic vertebrate brain with that of adults.

4. List the regions of the brain (with functions) from the “outside” of the brain, inward.